The SharePoint 2013 has become a powerful development platform with the addition of Apps. This enables to develop applications that can be used with different capabilities adding better advantages. The server side object model can be still used as Microsoft has made it still available with its full functionality in this version. However, the addition of App development platform has given new dimensions to SharePoint usability. It has made this framework to be more compatible to recent latest trends of web development. This new App model out-dates the old model in many aspects. Hosting is the primary leverage that is introduced to outnumber the advantages of server side platform.
Apps can be hosted on three different ways. These are high level hosting architecture that makes any code run beyond the host environment.
In SharePoint Hosted type can be implemented with custom business logic within the browser. List and Libraries can be accessed by this hosting method. In this architecture, apps are hosted independently within SharePoint.
In the Provider Hosted model, apps may be integrated with external servers such as cloud servers or other websites and applications. The codes exist within SharePoint with access to its functionality. In short, it is hosting your applications in another server via SharePoint. Therefore, this provides freedom to choose any host server even-though you are using the home platform.
Auto Hosted Model
Here, the databases that the app will require and the website will be hosted in the Windows Azure Website. The business logic can be hosted externally as in provider hosted model, however SQL Azure database and Windows Azure Website will be connected automatically with the application via SharePoint.
Using these new hosting platforms now developers will have greater freedom to integrate app with other tools and technologies. A wide variety of technologies such as JSON, REST, J Query and so on can be utilized while developing. Codes now can be modified and updated without changing the whole structure. Further, since custom code is independent of the SharePoint farm, no operation is possible hence increasing its stability.
Read effective management using SharePoint here.